"A fox knows many things, but a hedgehog knows one big thing..."

I've been pretty hard on experts as of late.  Actually, to be more precise (maybe like an expert?!?!), I've been hard on experts who try to predict the future.  I've been writing for the past couple of weeks or so on Philip Tetlock's book, Expert Political Judgement in which he discussed the results of his 20-year study on forecasting (for a description of the book, see my post Dart-throwing monkeys or check out Louis Menand's review in The New Yorker).  Tetlock found that experts weren't all that good at forecasting the future.

Here's the part where I totally contradict everything I've said so far.  I am only kidding.  Taken as a whole, Tetlock's experts weren't very successful at forecasting future events.  However, he did find that there were some experts that were more successful than others - or perhaps it's better to say that some experts weren't as bad as the others!  He divided his group of experts into hedgehogs and foxes, based on the philosopher Isaiah Berlin's 1953 essay, The Hedgehog and the Fox.  Berlin's title is in turn borrowed from the ancient Greek poet,  Archilochus who wrote that "A fox knows many things, but a hedgheog knows one big thing."  As an aside, the management guru Jim Collins also borrowed from Berlin and Archilochus when he developed his own hedgehog concept in his book, Good to Great.  

Okay, back to Tetlock.  Tetlock describes hedgehogs as follows:

...thinkers who "know one big thing," aggressively extend the explanatory reach of that one big thing into new domains, display bristly impatience with those who "do not get it", and express considerable confidence that they are already pretty proficient forecasters, at least in the long term.

Conversely, Tetlock described foxes as:

...thinkers who know many small things (tricks of their trade), are skeptical of grand themes, see explanation and prediction not as deductive exercises but rather as exercises in flexible "ad hocery" that require stitching together diverse sources of information, and are rather diffident about their own forecasting prowess.

Importantly, Tetlock's hedgehogs performed worse in those areas in which they specialized!  He did find that when hedgehogs did make a correct prediction (which again was rare), they were spectactularly right!  They predicted really rare and at times society-changing events.  Tetlock further elaborated on these themes in his most recent book, Superforecasting.

So what's the take-home message here? First, remembering The Linda Problem, we should all spend more time learning about probability and statistics.  Second, perhaps we should all be more like foxes and less like hedgehogs.  Tetlock describes a few lessons on how to be a better fox:

1. Don’t believe the world can be explained by one or two ideas. Reality is more complex.

2. When forming judgments, consult a diverse range of sources.

3. As the facts change, change your mind.

4. Question that on which everyone seems to agree

All in all, excellent advice.